Propriedades magnéticas em filmes finos de MoS2 produzidos pelo método de esfoliação em solvente

• Ano de defesa: 2020
• Autor(a) principal: Fonseca, Raphael Garcia Moraes da
• Orientador(a): Oliveira, Adilson Jesus Aparecido de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Carlos; Câmpus São Carlos
• Programa de Pós-Graduação: Programa de Pós-Graduação em Física - PPGF
• Palavras-chave em Português: Anisotropia magnética; Material bidimensional; Estrutura de van der waals
• Palavras-chave em Inglês: Magnetic anisotropy; Two-dimensional material; Van der waals structure
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/13782

In this work, thin films of molybdenum disulfide 2D (MoS2) were prepared at different temperatures (15, 25, 30 and 45 ° C) using the solvent exfoliation method. This process produces changes in the morphology and structure of the crystal lattice, and as a consequence, changes the magnetic properties of these films, in particular the magnetic anisotropy. The samples were characterized morphologically and structurally using techniques of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and High Resolution (HTEM), Raman Spectroscopy and X-ray Excited Electron Spectroscopy (XPS). The magnetic properties were investigated by the Vibrating Sample Magnetometry (VSM) technique, using a magnetometer with SQUID sensor. Our results show that the origin of the changes in the magnetic properties are due to several defects of vacancies of atoms found in the prepared films. A modified Hubbard model was proposed to adjust the magnetic data from measurable parameters associated with the electrons pinning in the vacancy and defects of the MoS2 samples. The changes in the magnetic anisotropy of the samples were investigated as a function of the external magnetic field applied in different directions and the results were discussed in terms of the energy balance of the spin-orbit interactions and the electronic orbital angular momentum with the crystalline field of the vacancy defects located on the zigzag edge of the MoS2 few-layer films.